Python DBus handle hibernate, sleep and resume

dbus_handler.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
__author__ = 'xanter'

#from datetime import datetime
import signal
import time
import dbus
import gobject
import urllib2
import os
from dbus.mainloop.glib import DBusGMainLoop


def handle_sleep(mode):
    if mode:
        print("Sleep")
        # TODO: allow to use custom commands
        os.system('i3lock')
    else:
        print("Resume")

DBusGMainLoop(set_as_default=True)     # integrate into gobject main loop
bus = dbus.SystemBus()                 # connect to system wide dbus
bus.add_signal_receiver(               # define the signal to listen to
    handle_sleep,                      # callback function
    'PrepareForSleep',                 # signal name
    'org.freedesktop.login1.Manager',  # interface
    'org.freedesktop.login1'           # bus name
)


loop = gobject.MainLoop()
loop.run()